How add captcha without php?

Question

This my code: the function check() is working, but the function ChangeCaptcha() didn't show letter in input type="randomfield" :

<body onload="ChangeCaptcha()">
  <input type="text" id="randomfield" disabled><br><br>                               
    <input id="CaptchaEnter" size="20" ><br><br>                         
    <button type="submit" onclick="check()">Log in</button>

  <script type="text/javascript">
    function ChangeCaptcha() {
      var chars= "1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
      var string_lenght = 6;
      var ChangeCaptcha = '';
      for (var i=0; i<string_length; i++) {
        var rnum = Math.floor(Math.random() * chars.length);
        ChangeCaptcha+= chars.substring(rnum, rnum+1);
      }
      document.getElementById('randomfield').value= ChangeCaptcha;
    }
    function check() {
      if (document.getElementById('CaptchaEnter').value == document.getElementById('randomfield').value) {
        window.open('http://www.lolila.hol.es', '_self');
      } else {
        alert('Pleace re-check the captcha!')
      }
    }
  </script>
</body>

What exactly is the problem you are having? What are you expecting to get? — tumultous_rooster, Feb 18 '16 at 08:30
Why would you do Client-side captcha validation? Read this: http://stackoverflow.com/questions/3196335/how-to-create-simple-javascript-jquery-client-side-captcha — Zlatan Omerović, Feb 18 '16 at 08:31
string_length is wrongly typed in assigning variable; change it and run — Gopalakrishnan, Feb 18 '16 at 08:32
in console: Uncaught ReferenceError: string_length is not defined ChangeCaptcha @ index.html:39 onload @ index.html:26 and in input type="randomfield" didn't show letter (captcha code) — Nazar Vovk, Feb 18 '16 at 08:34
@NazarVovk As I have clearly pointed out, you have a typo. This is why `string_length` isn't defined. You have defined `string_lenght` **Not** `string_length` — NewToJS, Feb 18 '16 at 08:35
@NazarVovk Very welcome, simple typo. Your browser console is you best friend! — NewToJS, Feb 18 '16 at 08:42

score 1 · Answer 1 · answered Feb 18 '16 at 08:45

I executed your code right here in chrome developer console:

it tells me you have a typo in your code because i does not know the variable: string_length. you declared it as string_lenght. To fix, change string_lenght => string_length.

The result:

function ChangeCaptcha() {
      var chars= "1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
      var string_length = 6;
      var ChangeCaptcha = '';
      for (var i=0; i<string_length; i++) {
        var rnum = Math.floor(Math.random() * chars.length);
        ChangeCaptcha+= chars.substring(rnum, rnum+1);
      }
      document.getElementById('randomfield').value= ChangeCaptcha;
    }

the result:

How add captcha without php?

1 Answers1